Hydrogen Vibrations Research Articles

Discovery of PdHx compounds using genetic algorithms and first-principles calculations

Abstract In the present work, the variable-composition crystal structure prediction algorithm USPEX was combined with first-principles calculations to systematically explore stable PdH x compounds in the pressure range from 0 to 100 GPa. The predicted structures are PdH, Pd4H5, Pd2H, and PdH4, of which PdH has previously been synthesized. The electronic structures show that these compounds can be metallic, with Pd states dominating at the Fermi level. However, the hydrogen atoms do not play a main role in the electronic properties; their vibrations do contribute to the electron–phonon coupling. The predicted Pd4H5 has a superconducting transition temperature of ∼13 K, which is higher than that of PdH (∼8 K in the experiment). Additionally, PdH, Pd4H5, Pd2H, and PdH4 can be classified as phonon-mediated superconductors, falling into the low-coupling regime. Our results demonstrate that as the hydrogen concentration is increased in PdH x compounds, the superconducting transition temperature rises due to hydrogen vibrations, which is consistent with the experiment. Hence, the present study paves the way for discovering new PdH x compounds with promising superconducting transition temperatures.

Investigating zero-point vibrations of solid hydrogen via statistical moment method

Zero-point vibrations of solid hydrogen are investigated by analyzing the molecular mean-squared displacement (MSD) and mean-squared relative displacement functions within the statistical moment method approach in statistical mechanics. Numerical computations of these thermodynamic properties were conducted for solid hydrogen from 0 K to its phase transition temperature using the Wigner-Kirkwood mean-field potential derived from the Buckingham exp-6 potential. We have shown that the quantum-mechanical zero-point vibrations play an important role at low temperature. And these thermodynamic quantities increase with temperature, suggesting that both thermal and quantum effects play a significant role near the liquid-solid phase transition. The favorable consistency between our findings and the recent experimental inelastic neutron scattering measurements of MSD attests to the potential of SMM as a novel approach for determining the atomic vibrations of solid hydrogen. This approach allows us to study these effects including the anharmonicity of lattice vibrations.

Role of Gd3+ ions in alumino borosilicate glasses studied through structural, optical and thermoluminescence characteristics for gamma dosimetry applications

This paper reports the structural, optical and thermoluminescence properties of Gd3+ ions incorporated alumino-borosilicate glasses, prepared through the melt-quench technique. The amorphous nature of the glasses is confirmed through XRD study. Network vibrations of borate and silicate groups, vibrations of hydrogen bonding and hydroxyl groups are realized via FTIR study. The Gd3+ transition peaks are absent in the near ultraviolet, visible and NIR regions, and the indirect bandgap values were determined through UV–Visible–NIR study. Photoluminescence measurements showed a concentration quenching in the glasses beyond 1.5 mol % of Gd3+ ions. Based on the thermoluminescence (TL) data, the 2 mol % of Gd2O3 doped glass (BSGD5) was chosen as optimum sample because of the presence of maximum TL intensity. The BSGD5 glass displayed TL response linearity in 0.25–1 kGy dose region giving a high signal sensitivity of 220,068 counts. g−1 kGy−1 in this region. With nearer tissue equivalence and a minimum detectable dose of 0.02 Gy, the suitability of BSGD5 glass for gamma dosimetry application was deducted. Electron spin resonance (ESR) study validated the presence of intrinsic defects in Gd3+ glasses which are responsible for changes in the intensity and shape of TL glow curves. Hence, from the obtained results Gd3+ doped alumino borosilicate glasses can be considered as potential candidates for gamma dosimetry application.

The investigation on exploring rare earth hydrides superconductors

This review provides a comprehensive overview of the challenges and potential solutions in the quest for high-temperature superconductivity using hydrogen-rich materials. Traditional superconductors often face limitations in terms of critical transition temperatures (Tc) and stability under high pressures. However, hydrogen-rich compounds offer promising avenues due to their strong electron-phonon coupling, elevated Debye temperatures, and high electronic density. Recent discoveries, such as H3S, have further invigorated the field. While an excess of H2-like units can adversely affect Tc, clathrate structures like CaH6 and YH6 present viable alternatives by fostering high symmetry. Rare earth hydrides, notable for their electron-donating capabilities, have undergone extensive testing. Isotope effect studies, as exemplified by LaH10 and LaD10, highlight the critical role of hydrogen vibrations in superconductivity. Ternary superhydrides incorporating dopant elements aim to reduce the pressure requirements for stability, with LaBeH8 emerging as a promising candidate, exhibiting a Tc of 110 K at 80 GPa. The review concludes by outlining future research directions, such as the incorporation of small-radius atoms to increase hydrogen content, a deeper understanding of the role of symmetry, and addressing challenges related to vibrational modes and structural stability.

Synthesis and FTIR Analysis of Cd Doped Nano Ni - Aluminates

Nano Ni – Aluminates (Ni0.5 Fe0.5 Al2O4) and Cd Doped Nano Ni – Aluminates (Ni0.5 Fe0.5 Al2-x CdxO4) where x = 0.2, 0.4, 0.6 and 0.8 were synthesized by co-precipitation method. Ammonium hydroxide was used as precipitating agent. The samples were characterized using Fourier transform infrared spectroscopy. FTIR spectrum for each unannealed sample of Ni0.5 Fe0.5 Al2 O4 and Ni0.5 Fe0.5 Al2-x Cdx O4 exhibit a broad band near 3450 cm-1 due to –OH stretching vibration of free hydrogen bonded hydroxyl group and a second typical absorption band at 1620 cm-1 resulting from deformative vibration of water molecules. Spectra for samples after annealing show peaks in the range of 900-450 cm-1 and 850-500 cm-1 showing presence of Al-O and Ni-O bonds respectively thus confirm the formation of metal oxides bonds while no peak was observed for –OH bond. A peak around 420 cm-1 is assigned to Cd-O bond.

Hydrogen vibration excitations of ZrH1.8 and TiH1.84 up to 21 GPa by incoherent inelastic neutron scattering

Hydrogen vibration excitations of fluorite-type $\mathrm{Zr}{\mathrm{H}}_{1.8}$ and $\mathrm{Ti}{\mathrm{H}}_{1.84}$ were investigated at pressures up to 21 and 4 GPa, respectively, by incoherent inelastic neutron scattering experiments. The excitations of both the samples were well described by quantum harmonic oscillator (QHO) over the entire pressure region of this study. The first excitation energies increased with increasing pressure, as described by the equations ${E}_{1}(\mathrm{meV})=141.4(2)+1.02(2)P$ (GPa) and ${E}_{1}\phantom{\rule{0.16em}{0ex}}(\mathrm{meV})=149.4(1)+1.21(8)P$ (GPa) for $\mathrm{Zr}{\mathrm{H}}_{1.8}$ and $\mathrm{Ti}{\mathrm{H}}_{1.84}$, respectively. Coupling with pressure dependence of lattice parameters determined by diffraction experiments, the relations between metal-hydrogen distance $({d}_{\mathrm{M}\text{\ensuremath{-}}\mathrm{H}})$ and ${E}_{1}$ of $\mathrm{Zr}{\mathrm{H}}_{1.8}$ and $\mathrm{Ti}{\mathrm{H}}_{1.84}$ at high pressures are found to be well described by the equations ${E}_{1}(\mathrm{meV})=1.62(9)\ifmmode\times\else\texttimes\fi{}{10}^{3}\phantom{\rule{0.16em}{0ex}}{d}_{\mathrm{M}\text{\ensuremath{-}}\mathrm{H}}^{\ensuremath{-}3.32\phantom{\rule{0.16em}{0ex}}(7)}(\AA{})$ and ${E}_{1} (\mathrm{meV})=1.47(21)\ifmmode\times\else\texttimes\fi{}{10}^{3}\phantom{\rule{0.16em}{0ex}}{d}_{\mathrm{M}\text{\ensuremath{-}}\mathrm{H}}^{\ensuremath{-}3.5(2)}(\AA{})$, respectively. The slopes of these curves are very steep compared to the previously reported trend in various fluorite-type metal hydrides at ambient pressure, suggesting that pressure and chemical substitution affect the hydrogen vibration excitations differently. The hydrogen wave function spreading estimated from the ${E}_{1}$ value assuming the QHO model showed the preferential shrinkage of the wave function to the tetrahedral sites, suggesting that the local potential field for a hydrogen atom shrinks more intensively than the tetrahedral site. The preferential shrinkage of the hydrogen wave function and the steep rise in the ${E}_{1}$ at a small ${d}_{\mathrm{M}\text{\ensuremath{-}}\mathrm{H}}$ under pressure are likely caused by the rigid metal ion core compared to hydrogen atoms and the resulting confinement of the hydrogen atom in the narrower potential field at high pressures.

The fingerprints of nifedipine/isonicotinamide cocrystal polymorph studied by terahertz time-domain spectroscopy

Cocrystal is constructed to improve physicochemical properties of active pharmaceutical ingredient and prevent polymorphism via intermolecular interactions. However, recent examples on cocrystal polymorphs display significantly different properties. Even though some analytical techniques have been used to characterize the cocrystal polymorphic system, it remains unclear how intermolecular interactions drive and stabilize the structure. In this work, we study the cocrystal polymorphs of nifedipine (NFD) and isonicotinamide (INA) using terahertz (THz) spectroscopy. Form I and form II of NFD-INA cocrystals show spectral fingerprints in THz region. Temperature-dependent THz spectra display distinguished frequency shifts of each fingerprint. Combined with solid-state density functional theory (DFT) calculations, the experimental fingerprints and their distinct responses to temperature are elucidated by specific collective vibrational modes. The vibrations of hydrogen bonding between dihydropyridine ring of NFD and INA are generally distributed below 1.5 THz, which play important roles in stabilizing cocrystal and preventing the oxidation of NFD. The rotations of methyl group in NFD are widely distributed in the range of 1.5–4.0 THz, which helps the steric recognition. The results demonstrate that THz spectroscopy is a sensitive tool to discriminate cocrystal polymorphs. It has the potential to be used as a non-invasive technique for pharmaceutical screening.

Exploring the Effect of the Number of Hydrogen Atoms on the Properties of Lanthanide Hydrides by DMFT

Lanthanide hydrogen-rich materials have long been considered as one of the candidates with high-temperature superconducting properties in condensed matter physics, and have been a popular topic of research. Attempts to investigate the effects of different compositions of lanthanide hydrogen-rich materials are ongoing, with predictions and experimental studies in recent years showing that substances such as LaH10, CeH9, and LaH16 exhibit extremely high superconducting temperatures between 150–250 GPa. In particular, researchers have noted that, in those materials, a rise in the f orbit character at the Fermi level combined with the presence of hydrogen vibration modes at the same low energy scale will lead to an increase in the superconducting transition temperature. Here, we further elaborate on the effect of the ratios of lanthanide to hydrogen in these substances with the aim of bringing more clarity to the study of superhydrides in these extreme cases by comparing a variety of lanthanide hydrogen-rich materials with different ratios using the dynamical mean-field theory (DMFT) method, and provide ideas for later structural predictions and material property studies.

Emerging lignocellulosic ionic liquid biomass pretreatment criteria/strategy of optimization and recycling short review with infrared spectroscopy analytical know-how

• Pretreatment of lignocellulosic biomass (LCB) using ionic liquid solvent review in general. • Pretreatment optimization with recycling technique on LCB review information. • Fourier Transform Infrared Spectroscopy (FTIR) shift and change of FTIR peaks/curve prediction/relationship comparing the untreated to the pretreated lignocellulosic biomass sample of oil palm source of oil palm frond (OPF), empty fruit bunch (EFB), oil palm trunk (OPT) and micro crystalline (MCC) biomass analytical area under the curve data. Pretreatment of various types of lignocellulosic biomass (LCB) being shortly reviewed as criteria concerning emerging pretreatment solvents, recycling strategies and optimization. Review findings presented include pretreatment methods, recycling techniques, ionic liquid types, optimization parameters (dependent/independent), optimization model and references. In this article, original investigated research Fourier Transform Infrared Spectroscopy (FTIR) pretreatment data on oil palm frond (OPF), empty fruit bunch (EFB), oil palm trunk (OPT) and microcrystalline cellulose (MCC) were also presented, aiding the indirect indicator strategy of the effect of pretreatment via FTIR analysis to support the criteria analysis. The strategy covers certain spectroscopy changes when 1-ethyl-3-methylimidazolium acetate [EMIM]Ac and electron beam irradiation (EBI) pretreatments on untreated and treated LCB samples, predicting shift in peaks or change of shape of the FTIR curve at specific wavenumber spectral region. Fundamentally, the obvious decrease of area under the curve values relationship with the pretreatment effects for three (3) spectroscopy FTIR functional groups representing stretching and vibration of oxygen, hydrogen and carbon combinations within the range of 3125 to 3600, 2850 to 2950 and 890 to 1200 cm −1 on four (4) different microcrystalline cellulose conditions of being untreated together with ionic liquid pretreatments of 50% (v/v) and 100% (v/v) [EMIM]Ac and finally with radiation pretreatment of 1000 kGy EBI conditions, can be useful for the criteria analytical understanding spectroscopically.

Isotopic dependence of the frequency of optical vibrations in molybdenum monohydride

It is currently known that three hydrides – PdHx, MoHx, and TiHx – exhibit an inverse isotope effect in superconductivity. Namely, the phase with a heavier hydrogen isotope, deuterium, has a higher critical temperature. Hydrides and deuterides of palladium have intensively been studied both experimentally and theoretically, but the origin of the isotope effect has not been established with certainty. The commonly accepted explanation is that the effect is likely to be due to the strong anharmonicity of the optical hydrogen vibrations, which was considered to be responsible for the large deviation of the ratio of the fundamental optical frequencies ωH/ωD = 1.51 from the harmonic value 2 ≈ 1.41. In the present paper, powder samples of MoH1.1(1) and MoD1.07(3) were synthesized under a hydrogen / deuterium pressure of several gigapascals and studied by inelastic neutron scattering (INS) at ambient pressure and T = 10 K. The INS study demonstrated that optical vibrations of H atoms in MoH1.1 and D atoms in MoD1.07 are harmonic and the ratio of fundamental optical frequencies ωH/ωD = 1.44 is close to the harmonic value 2 ≈ 1.41. This shows that anharmonicity is not a necessary condition for the presence of the inverse isotope effect. The MoD1.07 sample was additionally studied by neutron diffraction (ND) at ambient pressure and T = 100 K. In agreement with previous ND results for MoH1.2, the ND study of MoD1.07 showed that deuterium atoms occupied almost all octahedral interstitial sites in its hexagonal close-packed metal lattice and formed a NiAs-type crystal structure with the composition close to MoD. The overstoichiometric composition MoD1.07 of the deuteride is likely to result from a small fraction D/Mo ~ 0.07 of deuterium atoms partially occupying the tetrahedral interstices.

Size-Dependent πg + πu Combination Band Intensities of Polyynes C2nH2 (n = 1-9) Analyzed by the Local CCH Bending and the Linear Response Functions.

Polyynes (C2nH2) show the unusually strong πg + πu combination bands in the infrared absorption spectra. We calculated them as the first overtone of the local CCH bending; the strong intensities are interpreted as a consequence of the large-amplitude bending vibration of the acidic acetylenic hydrogen combined with the size-dependent π electron conjugation. Our theoretical calculations show that the absorption intensity increases steadily and their increase rate is gradually slowed down by increasing the number of acetylene units up to n = 9. However, the calculated vibrational wavenumber converges quickly in agreement with the experimental observation. The second-order electron density deformation caused by the local CCH bending was analyzed using the linear response functions, including the linear and nonlinear contributions, to explain the n dependence. The easily polarizable π electron density caused two kinds of deformation-dominant but dark δxx-yy type and minor but bright σ type. Both of them exhibit interesting zigzag sign alternations, consistent with the law of alternating polarity of Coulson and Longuet-Higgins. The electron density polarization in these intra- and interacetylene units induces a large axial component molecular dipole moment, contributing to the intensity that increases with n. The difference between the curvilinear and rectilinear bending coordinates is interpreted within the present theoretical scheme.

Quantification of the nonlinear susceptibility of the hydrogen and deuterium stretch vibration for biomolecules in coherent Raman micro-spectroscopy.

Deuterium labelling is increasingly used in coherent Raman imaging of complex systems, such as biological cells and tissues, to improve chemical specificity. Nevertheless, quantitative coherent Raman susceptibility spectra for deuterated compounds have not been previously reported. Interestingly, it is expected theoretically that -D stretch vibrations have a Raman susceptibility lower than -H stretch vibrations, with the area of their imaginary part scaling with their wavenumber, which is shifted from around 2900 cm-1 for C-H into the silent region around 2100 cm-1 for C-D. Here, we report quantitative measurements of the nonlinear susceptibility of water, succinic acid, oleic acid, linoleic acid and deuterated isoforms. We show that the -D stretch vibration has indeed a lower area, consistent with the frequency reduction due to the doubling of atomic mass from hydrogen to deuterium. This finding elucidates an important trade-off between chemical specificity and signal strength in the adoption of deuterium labelling as an imaging strategy for coherent Raman microscopy.

Vibrational properties of High Entropy Alloy based metal hydrides probed by inelastic neutron scattering

The vibrational properties of several High Entropy Alloy (HEA) based metal hydrides are investigated by inelastic neutron scattering (INS). HEAs have recently emerged as a new type of materials with a wide range of intriguing properties and potential applications such as hydrogen storage. The special properties of HEAs are believed to originate from the disordered lattice and internal strain that is introduced from the differences in atomic radii. This makes HEA hydrides provide an intriguing situation for the local H coordination, of several different transition metals. INS spectra were collected on a series of HEA-based metal hydrides starting with TiVNbHx and subsequently adding Zr and Hf to increase the atomic size mismatch. A general feature of the spectra are the optical peaks centered around an energy loss of 150 meV that can be attributed to hydrogen vibrations in a tetrahedral environment. Upon the addition of Zr and Hf, a shoulder appears on the optical peak at lower energy transfers that after comparison with in silico calculated INS spectra is indicative of hydrogen also occupying octahedral sites in the structure.

Hydrogen Vibration in Hydrogen Storage Materials Investigated by Inelastic Neutron Scattering

Hydrides are promising hydrogen storage materials owing to their higher gravimetric and volumetric hydrogen densities compared to compressed hydrogen gas and liquid hydrogen. Hydrogen is absorbed by different compounds (formation reaction of hydride) and thus exhibits different states—elemental hydrogen (H0), hydride ion (H−), and covalently bonded hydrogen (Hcov.)—in hydrides. The absorbed hydrogen is released as hydrogen gas (decomposition reaction of hydride). Therefore, it is important to understand hydride formation and decomposition based on the nature of chemical bonding of hydrogen (hydrogen states) in hydrides. Although it is difficult to directly observe hydrogen states, inelastic neutron scattering (INS), a powerful and useful technique, can be employed for this purpose as hydrogen vibrations in hydrides depend on its state. Herein, we provide an overview of INS studies of hydrogen vibrations in representative hydrides which are potential hydrogen storage materials. In particular, mode assignments focused on hydrogen states, local atomic arrangements around hydrogen atoms, hydrogen release reactions, and hydride formation processes based on observed hydrogen vibrations through INS are reviewed in this paper.

Hydrogen Visualization in a Fuel Cell Anode By Raman Imaging

Development of durable commercial/heavy fuel cell (FC) vehicles is required to decrease carbon dioxide emission from commercial/heavy vehicles. The mileage of heavy vehicles is far higher than that of passenger vehicles. Because FC stacks in vehicles deteriorate during long-term operation, their lifetime should be maximized by increasing durability. To improve FC stack durability, we must avoid catalyst degradation. When the hydrogen supply on the anode catalyst surface is inadequate, carbon of the cathode catalyst is oxidized with water. This occurs where there is insufficient hydrogen, such as at anode outlet during cell starting or water flooding. It is therefore important to prevent deterioration of FC operation caused by inadequate hydrogen. In stacks where the anode gas is circulated, nitrogen permeates and remains at the anode until it is exhausted, which lowers hydrogen concentration. Moreover, hydrogen is consumed in the piling direction, so its concentration is lower downstream. This leads to degradation at the anode outlet, so a high hydrogen flow rate is required during operation.To optimize hydrogen supply through feedback control, it is beneficial to measure the local hydrogen partial pressure. Hydrogen distributions exist in the reactive plane, gas manifolds, and piping system. To avoid FC deterioration caused by insufficient hydrogen, hydrogen concentration needs to be measured in the in-plane direction. However, it is difficult to measure hydrogen distribution in the in-plane direction. Some commercial sensors may affect FC materials. General hydrogen sensors are unsuitable for hydrogen concentrations over 4% inside FC systems.Raman spectroscopy is a useful hydrogen detection method. Generally, leaked hydrogen gas is intermittently detected with Raman spectroscopy. The intensity of Raman scattering is about 10−4 times that of Rayleigh scattering, and low-density gas scattering is weak compared with that of a liquid or solid. However, the Raman shift of hydrogen vibration (4160 cm−1) is far larger than that of other materials and does not require high wavelength resolution. Moreover, the hydrogen partial pressure in FC systems is high and easily detected.We developed a new method to measure the hydrogen Raman scattering from the reacting surface of an operating FC. During operation, hydrogen is consumed in the anode channel and its partial pressure drops near the outlet. To confirm this phenomenon with Raman spectroscopy, we needed to detect scattering light from the anode channel during cell operation. This measurement also required optics able to resolve very weak hydrogen Raman scattering. For these reasons, we fabricated a visualization cell that transmitted pump and scattered light without gas leakage. Pump light was introduced into a flow field in a channel with a depth of 1 mm, so the channel worked as an optical path . The optical path was from a mirror on the cathode flow field toward the anode to avoid interference with sealing materials. Sapphire windows were included in the anode flow field to allow visualization of scattered light.Using this cell and an Intensified Charge-Coupled Device (ICCD ) camera, we vertically observed Raman scattering from hydrogen. We included a bandpass filter with a center wavelength of 420-nm and halfwidth of 10 nm inside the camera lens to capture images of 417-nm scattered light from hydrogen excited by 355-nm pump light through the filter. A 355-nm notch filter was also added to remove the optical noise from Rayleigh scattering, allowing visualization of only hydrogen.Before the measurement, scattering intensity was calibrated using 100% hydrogen and nitrogen to clarify the relation between scattering intensity and partial pressure. The flow field was filled with 100% hydrogen (100 kPa) and an intensity distribution was obtained. Pure nitrogen was also measured to evaluate the dark noise and the correlation between intensity and hydrogen partial pressure. Local partial pressure was determined from the intensity at a desired point.We then measured the scattered light during cell operation at 100 kPaG. Hydrogen with a stoichiometric ratio of 1.1 diluted 45% by nitrogen was supplied to the cell to mimic stack operation. The cell operated at 0.5 A/cm2. The scattering distribution was measured at 10 Hz and ten measurements were integrated to determine hydrogen partial pressure distribution from the scattered light intensity . Hydrogen partial pressure decreased from 80 to 40 kPa along the in-plane flow, consistent with our rough predictions of 90 and 38 kPa, respectively. This data was thought to be affected by the sensitization noise from the photomultiplier tube elements in the ICCD camera. Suppressing optical and electronic noise or conducting an imaging process with dispersion treatment will allow detection of various gases with this Raman method.

Phonon investigation on the interaction of hydrogen on the missing row Pt (110)-(1x2) surface

The phonon calculations of hydrogen when adsorbed on the missing row Pt(110)-(1x2) surfaceusing the Ultrahigh Vacuum (UHV) model were studied. The calculations were based on a combinationof Density Functional Theory (DFT) and the approximation of hydrogen vibrations on thesurface. The harmonic vibration of H on the Pt surface was used for the calculation in this study. Atthe hydrogen coverage of 1ML for the model surface (when H completely covering the Pt surface),the interaction formed at the edge of the first layer (short bridge - R) was the most stable. The lessstable positions were recorded as the bridge position between two atoms on a horizontal row inthe second layer (trough - T), the top position of the second surface layer - fcc (F), the bridge positionof the second surface layer - hcp (F'), and the least stable position was the top position of thefirst layer (T'). When accounting the quantum calculation for the model, the adsorption energy ofhydrogen at the short bridge position increased by 90 meV, and the stable adsorption order of hydrogenchanged with the most stable positions ware R, T, T', F', F respectively. This demonstratesdthe significant influence of quantum effects on the adsorption model.

Host–guest inclusion complex of β-cyclodextrin and benzoic acid in water–ethanol solvents: spectroscopic and thermodynamic characterization of complex formation

In this study, an inclusion complex of benzoic acid with β-cyclodextrin (BA-βCD) was obtained from water–ethanol solvents. The yield of complex synthesis in binary mixtures is greater than in water and reaches maximum value at 0.10 mol fraction of ethanol. Results of FTIR spectroscopy analysis showed that the main difference in the spectra of the acid and inclusion complex was observed in the frequency ranging from 2500 to 3100 cm−1, corresponding to aromatic hydrogen vibrations. These vibrations are highly attenuated in complex. Phase solubility and differential scanning calorimetry studies revealed that the inclusion complex was obtained with 1:1 stoichiometric ratio and the solubility of benzoic acid increased with an increase in β-cyclodextrin concentrations in water. The logarithm of stability constant in water was found to be lgK = 1.99. The thermodynamic parameters for the reaction of (BA-βCD) complex formation in H2O–EtOH solvents were determined from calorimetric experiments carried out by means of the calorimetric titration system TAM III (TA Instruments) at T = 25 °C. The heat effects of mixing β-cyclodextrin solutions with benzoic acid were obtained from water–ethanol mixed solvents containing X(EtOH) = (0.00, 0.10, 0.20 and 0.30) mole fraction at pH = 3.6 and T = 25 °C. However, at X(EtOH) = 0.30 mol fraction, according to the calorimetric titration data, no complex formation occurs. When transferring from H2O to H2O–EtOH solvents, complex stability decreases from lgK = 2.4 to lgK = 0.7, wherein the reaction exothermicity increases from − 12.2 kJ mol−1 to − 44.3 kJ mol−1. An increase in the exothermicity of complexation is accompanied by a decrease in the entropic contribution to the change in the reaction Gibbs energy.

Vibrational Study of the Hydrogen Adsorption on the Missing Row Platinum (110) Surface

The hydrogen vibration was investigated to analyze its affect on the hydrogen adsorption on the missing row platinum surface (H/Pt(110)-(1\(\times\)2) model) in the ultrahigh vacuum (UHV). The density functional theory (DFT) combined with the approximation oscillation of the hydrogen atom on the surface was used. When the hydrogen coverage ΘH on the surface is 100% (\(\Theta\) = 1 ML), and taking into account the vibrational effect, the bond formed at the edge of the first layer (short bridge) is the most stable site. The vibrational effect on the adsorption model H/Pt(110)-(1\(\times\)2) is significant.

Effects of peanut shell and skin extracts on the antioxidant ability, physical and structure properties of starch-chitosan active packaging films

In this study, the antioxidant ability of peanut shell and skin extracts and their effects on the physical and structure properties of starch-chitosan film were investigated. The results showed that the DPPH radical scavenging ability of peanut skin extracts was significantly higher than the peanut shell extracts. This could be due to the rich rutin and 4-O-caffeoulquinic acid existed in the peanut skin extracts. When added the peanut skin and shell extracts into the starch-chitosan film, the apparent viscosity of film forming solution at 100 s−1 decreased. Moreover, water vapor permeability and swelling of film decreased with the addition of peanut skin and shell extracts. Two peanut extracts also increased the color L* and opacity of film. The tensile strength of film increased with the addition of peanut skin extracts, and decreased with peanut shell extracts. The addition of two extracts also resulted in the increase of endothermic temperature of starch-chitosan film. But there were no new peaks appeared in the FTIR image. Only the peaks at 3276 cm−1, 1382 cm−1, 1249 cm−1 shifted to 3273 cm−1, 1385 cm−1 and 1258 cm−1, which implied the peanut shell and skin extracts disturbed the hydrogen bond and vibration of molecular chain in film matrix.

The physical structure and surface reactivity of graphene oxide

The structural configuration of graphene oxide and its surface reactivity were investigated experimentally and clarified on the bases of time-independent density functional calculations (DFT). The physical structure was examined by transmission electron microscopy, infrared absorption, and X-ray diffraction parallel to radial distribution analysis. Surface reactivity was examined using N2-adsorption at 77 K and the kinetic of the adsorption of Ni2+, Cd2+, and Pb2+ ions at 300 K. The lattice structure of the material was hexagonal with unit cell a = 2.455 Å and c = 8.64 Å and with layer-layer distance of 4.32 Å. This structure is undulated in response to existence of oxygen atoms that shape surface topological imperfections and breaks the planner regularity. The undulation distance comprises 0.3 Å. The specific surface area was found 60.3 m2/g with about 50% of this area were available to adsorption of 2+ ions due to surface polarization. The vibration frequencies observed in FTIR are identified by DFT calculations and showed that the structure acts as an extended quantum system for which Pauli blocking prevents existence of two modes of marginal hydrogen vibrations within the same sheet.